Well, your friend decision is reasonable if don't know the right thing to do . You should have a sure way of repaying your loan otherwise you shouldn't borrow else you would be gambling or big risk. I'd suggest going for a vehicle that can generate income for you to repay the loan assuming you end up borrowing. If a used or new car can't do this for me, I wouldn't go for it.
I would go for particular brand of used car that can be used to generate income, that last long and is way cheaper than its new alternative. In my opinion, it's better to go for high quality used products if want to reduce cost and still successfully & safely solve the problem the new could've solved for you.